If the full path name of the DLLs are in the file then this should work:
Move-Item -Path (Get-Content x:\directory\file-with-dll-names.txt) -Destination y:\new-directory
If you have only the DDL name, and not the full path, in the file then this should work:
Get-Content x:\directory\file-with-dll-names.txt |
ForEach-Object{
Move-Item -Path "I:\source-directory\$_" -Destination y:\new-directory
}